Create a prototype spectrogram to handle real-time CBF signals

Currently CIPA have to slow down their testing in order to be able to capture data that can run on a spectrogram signal display. If successful this approach will then allow auto and cross power spectra across long integrations at full line rate to ensure expected covariance without the need to store large data volumes.

The feature has been completed with code available on GitLab at https://gitlab.com/ska-telescope/csp-rdma-spectrogram.
It supports receiving single or dual polarised signals, and in the case of dual polarisation it calculates cross-power in addition to the power in each polarisation.
The input is supported as complex 16 or 32 bit, expressed either in floating point (FP16 or FP32) or integral (short or int).
In System Demo 8.6 a throughput of 65Gbps was demonstrated, well above the 12.5Gbps required by CIPA for real-time visualisation from their dish receiver firmware. The demo used an additional C++ file called SimulatedSignalGenerator.cpp, which can be used to test different combinations of input options.
There are optional windows (pre-FFT) that can be selected: Blackman, Dolph Chebyshev, Flattop SR785, Flattop HFT70, Flattop HFT248D,
Hanning, Kaiser.
During the Innovation Sprint a python script provided by CIPA to test cross-power will be integrated as a test signal generator.